Reasons why not to use UPX (and other executable compressors

[slashbeast]

Reasons why not to use UPX (and other executable compressors).

- more ram usage
- lower performance
- whole code of programm is loaded, not on demand
- it doesn't allow to share memory so code is loaded to memory more than one time

Can I count that next version of TC would be released without compression?

[karlchen]

Well, I would not bet on it.
Yet, as for different reasons - some of which were mentioned by you - people need TC uncompressed, here is the link to the uncompressed TC 6.53 executable:

https://plugins.ghisler.com/img/unpack32_653.exe

You may have a look at the complete thread where I got the link from here:
http://ghisler.ch/board/viewtopic.php?t=6634&highlight=uncompressed

Karl

[Hacker]

slashbeast,

- lower performance

Roman

[nevidimka]

2slashbeast

- more ram usage

Not in all cases.

- lower performance

What kind of performance do you mean? Starting the program? Then you have to consider time for harddisk reading and time for unpacking.

- whole code of programm is loaded, not on demand

Only if a program use such techniques.

- it doesn't allow to share memory so code is loaded to memory more than one time

Only important if you start multiple instances.

[Lefteous]

What are the (dis-)advantages of using the compression provided by NTFS compared to executable packers and to umcompressed executables (beside the fact that the NTFS compression doesn't result in very small files?

[Hacker]

Lefteous,
You cannot distribute files with NTFS compression.

Roman

[nevidimka]

You cannot distribute files with NTFS compression.

It's possible - it's only a question of your installer.

What are the (dis-)advantages of using the compression provided by NTFS

You cannot use NTFS compression on FAT32 (or other FS).

beside the fact that the NTFS compression doesn't result in very small files

That's the big disadvantage:
TC V6.53
Uncompressed: 2.320.420 Bytes
NTFS: 1.622.016 Bytes
ZIP(TC): 1.101.824 Bytes
UPX: 837.156 Byte
7z (Ultra): 757.685 Bytes (EDIT)

Maybe a 7z-based installer (e.g. Inno-Setup) will be create a smaller installation file.

[gigaman]

2slashbeast

- more ram usage

Not in all cases.

When not?

- whole code of programm is loaded, not on demand

Only if a program use such techniques.

No. The original post (which I mostly agree with, even though the impact probably won't be that big) is refering to Windows memory management. Windows itself loads only the needed parts (on-demand) of the executable into memory. With the compressed executable, the whole file is loaded and unpacked there.
Besides, when a piece of the code is not used for a longer time, Windows may decide the swap it out. For uncompressed executable, it may simply discard (forget) the block - it can reload it from the file when needed. For compressed executable, it has to write it into the swap file first - because there's nowhere to reload it from.

[Lefteous]

2Hacker

You cannot distribute files with NTFS compression.

I'm sorry I think this thread is about executing UPX compressed files not about these files in installers. In installers the compression ratio/less overhead combination - or better - the resulting size is critical.

2nevidimka
I know all this. I mean are there other disadvantages? Imagine the conclusion would be that UPX is really bad in memory usage, performance, loading speed or whatever. Would it be a good decision to use this compression instead of the completely uncompressed executable?

[Hacker]

Lefteous,

I think this thread is about executing UPX compressed files

I think this thread is about disadvantages of using UPX in general.

Roman

[Lefteous]

2Hacker

I think this thread is about disadvantages of using UPX in general.

All the disadvantages named by the thread starter applies to running upx compressed executables only.

[Hacker]

Lefteous,
So I added another point of view.

Roman